The use of human umbilical cords as vascular grafts in lieu of saphenous veins is disclosed in the prior art. The umbilical cords are processed for subsequent use in a living body. The umbilical cords are shaped and cured on a mandrel. Holman in U.S. Pat. No. 4,241,794 discloses a method of shaping a human umbilical cord to a configuration determined by a mandrel. The mandrel can have a J-shape or a U-shape. The umbilical cord is mounted on the mandrel and treated with alcohol to shrink the cord to the shape of the mandrel. An aldehyde solution is used to fix or cure the umbilical cords on the mandrel. The mandrel is then removed from the cured umbilical cord. The mandrel is a solid one-piece member of plastic, such as polyethylene. The plastic material of the mandrel is difficult to shape and machine to an accurate configuration. Accurate tolerances on plastic mandrels cannot be maintained. Metal mandrels are difficult to use to shape and cure umbilical cords, as these mandrels cannot be easily inserted into the lumen of an umbilical cord or withdrawn from a cured umbilical cord.